1. Field of the Invention
This invention relates to a method of securing a body between two imperforate sheets and more particularly in its preferred form to a method of skin packaging and a skin package formed by the method.
2. Prior Art
So-called skin packages have now become well known in the art. With the typical skin package, a permeable base sheet is provided. With one form of skin packaging, a surface of the base sheet has been coated with an adhesive and the adhesive then perforated to provide a permeable layer.
This sheet is positioned over a vacuum chamber with the adhesive side up. The product to be packaged is positioned on the adhesive-treated surface. A film of thermoplastic material is then heat softened and brought down over the product and the sheet. The vacuum chamber is operated to establish a pressure differential such that the thermosoftened sheet is forced down over the product into an intimate, bonded contact with the adhesive surface of the base sheet.
In other forms of skin packaging, adhesive is not applied to the base sheet, but rather a treated film which will become adhesively secured to the base sheet is utilized. When the film is heat softened and forced into contact with the sheet through pressure differential, it bonds to the sheet around the product being packaged.
There have been proposals for providing selected imperforate areas in the base sheet. For example, when packaging a soft product, it has been proposed to provide a protective ring around the product and position the product on an imperforate area. When the plastic film is forced down against the base sheet, it adheres around the protective ring but is not drawn down into the ring and against the soft product. While there have been such proposals, formation of the package has nonetheless relied upon the permeability of the base sheet.